Modeling phoneme perception. I: Categorical perception

Area of Science:

• Psychoacoustics
• Speech Perception
• Auditory Neuroscience

Background:

• Speech perception research often investigates the categorical nature of phoneme processing.
• Understanding how listeners discriminate between speech sounds is crucial for models of auditory perception.
• Previous studies have explored categorical perception in vowels and consonants with varying results.

Purpose of the Study:

• To compare the categorical perception of stop consonants and vowels.
• To investigate the influence of experimental paradigms on speech sound discrimination.
• To determine if different theoretical frameworks are needed for consonant and vowel perception.

Main Methods:

• Conducted auditory discrimination experiments (AX and 2IFC) using natural speech stimuli.
• Varied experimental conditions, including fixed and roving stimulus sets.
• Analyzed both discrimination accuracy and phoneme identification responses.

Main Results:

• Stop-consonant perception demonstrated high categoricality, with discrimination closely mirroring identification.
• Vowel perception was less categorical, showing greater variability across experimental paradigms.
• Consonant discrimination was less susceptible to range effects compared to vowel discrimination.

Conclusions:

• Findings suggest distinct memory systems for processing stop consonants and vowels.
• Dual-process theory (DPT) may explain consonant perception, while trace-context theory (TCT) may explain vowel perception.
• A combination of theories is likely necessary to fully account for speech sound discrimination differences.